Electric discharge apparatus



An .19,1941." 'HWLORD 2,253,185

ELECTRIC DISCHARGE APPARATUS Filed Aug. 31, 1940 I nvent Or: H aro ldW Lord His Attorney.

Patented Aug. 19, 1941 ELECTRIC nrscnaaer: mana'rus Harold W. Lord, Schenectady, N. Y., assignor to General Electric Company, a corporation of New York Application August 31, 1940, Serial No. 355,045

BClaims.

My invention relates to apparatus for eflectingthe starting of an electric discharge device,

such as an electric discharge lamp, which is arranged to be operated from a constant current supply circuit and is provided with electrodes one or more of which are adapted to be heated before the discharge in the device is started. One object of my invention is to provide im proved apparatus of this character by which the application of the starting voltage is delayed until the temperature of the heated electrode or electrodes has reached the desired point. An-

other object of my invention is the provision in such apparatus of means for producing a more rapid electrode heating.

My'invention will be better understood from the following description taken in connection with the accompanying drawing, and its scope will be pointed out in the appended claims.

In the single figure of the drawing which is a circuit diagram illustrating one embodiment of my invention, I is an electron discharge device such for example as a sodium lamp shown having the spaced filamentary electrodes 2 and 3 which when the device is operated from an alternating current circuit alternately function as cathodes. The electrodes 2 and l are connected at one end respectively through the leads l and I with the constant current supply circuit 6 which is shown including the usual film cut-out 1 arranged between the connecting leads.

Associated with the device I is the transformer Ill, on the core ll ofwhich are the four windings II, It, It, and I5. Winding i3 connects through the contacts of the relay It with the opposite ends of the electrodes 2 and 3, thereby constituting a short circuit across the device I, the current ofthe circuit 6 being passed through the electrodes during the initial heating period. At this time the winding it functions as the primary of the transformer, the windings l2 and It functioning as secondary windings which by connecting across the electrodes 2 and 8 respectively supply supplemental heating current to those electrodes. If, for example, the current of the constant current circuit is 6.6 amperes the tential diiferencebetween the leads 4 and i. The winding of the relay IB is connected in series with the capacitor l1 and the secondary winding IS, the voltage of which supplements the voltage across the leads. During the heating interval this combined voltage of the winding II and that across the leads is insumcient to operate the relay; however, when the electrodes have reached their desired electron emitting temperature the voltage across the leads 4 and I will have increased to .such a value that it, together with the augmented voltage of the winding l8 due to the higher voltage across the leads, will cause the operation of the relay, thus opening the shunt circuit including the'winding l3. By

so doing, the voltage of the supply circuit is applied across the device which starts the discharge therein. 7

During the normal operation of the device the windings I! and I4 carry a small current by reason of the voltage drop through the electrodes and at this time these windings fimction as the primary of the transformer. The voltage then induced in the winding l5, taken together with the voltage between the leads 4 and I, is sum- I cient to maintain the relay in open cirbuit position. The capacitor I1 is constructed to offer a minimum amount of impedance, the purpose of the capacitor being to prevent any direct current due to lamp rectification from flowing through the relay and transformer windings.

total current flowing through the electrodes dur- I have shown the particular embodiment described above as illustrative of my invention and it will be apparent that various modifications may be made without departing from the spiritand scope of my invention which modifications letters Patent of the United States, is:

1. In combination, an electric discharge device having spaced electrodes arranged to be connected in a constant current alternating supply circuit, means for producing an initial heating of one of said electrodes comprising means for passing said current therethrough and a transformer having its primary connected to be,

energized by said current and its secondary connected to supplement said current in said electrode.

2. In combination, an electric discharge device having spaced electrodes arranged to be connected in a constant current alternating supply circuit, means for producing an initial heating of said electrodes comprising means for passing said current through said electrodes and a transformer having its primary connected between said electrodes and having a plurality of secondary windings each connected across one.

of said electrodes to supply a supplemental current thereto.

3. In combination, an electric discharge lamp having filamentary electrodes, means for connecting saidlamp in a constant current circuit, means for passing the current of said circuit in series through said electrodes to initially heat them, and means responsive to the increase in voltage applied to said lamp due to the heating of said electrodes andthe properties of said circuit for opening the circuit between the electrodes.

4. In combination, an electric discharge lamp having filamentary electrodes adapted to be initially heated by the passage of current therethrough, means connected with one end of each of said electrodes for including said lamp in a constant current circuit, a switch connected between the opposite ends of said electrodes and means responsive to the increase in voltage between the first mentioned ends of said electrodes .as the electrodes become heated for opening said switch.

5. In combination, an electric discharge lamp having filamentary electrodes adapted to be ininecting said opening means and said secondary in series between the first mentioned ends of said electrodes.

6. In combination, an electric discharge lamp having fllamentaryelectrodes adapted to be initially heated by the passage of current therethrough, means connected with one end of each of said electrodes for including said lamp in a constant current circuit, a transformer 'having a primary and a plurality of secondaries, means connecting a-secondary across each of said electrodes, a switch connected in series with said primary between the other ends of said elec-- trodes, an opening magnet for said switch, and means connecting said magnet and another secondary in series between the first mentioned ends of said electrodes.

V HAROLD W. LORD. 

